<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Js作业1</title>
    <script>
            function changeColor(){
                document.bgColor= "red";
            }
        </script>
        </style>
</head>
<body>
        <script>
            var i;
            i=1;
            document.write(typeof(i)+"<br/>");
            i=9.9;
            document.write(typeof(i)+"<br/>");
            i="hello";
            document.write(typeof(i)+"<br/>");
            i=true;
            document.write(typeof(i)+"<br/>");
            i=new Date();
            document.write(typeof(i)+"<br/>");
        </script>
        <script>
            var i;
            var j;
            for( i=1 ; i<=9 ; i++){
                for( j=1 ; j<=i ; j++){
                document.write(j+"*"+i+"="+j*i+"&ensp;");
                                     }
                document.write("<br>");
               }
        </script>
        <button onclick="changeColor()">点击按钮变色  </button>
</body>
</html>